JamSys: Coverage Optimization of a Microphone Jamming System Based on Ultrasounds

Abstract

With the development of digital devices, the recording process has become increasingly easier to conduct. However, the portability of the recording devices has also made recording difficult to monitor. If private conversations are illegally recorded, it will cause serious secret-leakage events. Therefore, it is imperative to prevent unauthorized recordings. Recent works have demonstrated that the nonlinearity effect of microphones can be leveraged to interfere with microphone recording using ultrasounds. However, an ultrasonic array has a limited jamming area. The design of an anti-recording system composed of multiple ultrasonic arrays remains to be addressed. In this paper, a jamming system, JamSys, is presented to prevent eavesdropping in a given region. We propose a new scheme composed of the angle coverage model and the modified harmony search algorithm (MHSA) to optimize the deployment of ultrasonic arrays, which achieves the maximum jamming area with the given number of arrays. In the simulation and experiments, three different optimization algorithms, the MHSA, the genetic algorithm (GA), and the regular coverage algorithm (RCA) are compared. The MHSA is demonstrated to provide the best results.